Method of adsorptive gas separation using thermally conductive contactor structure

ABSTRACT

A method of adsorption allows separation of a first fluid component from a fluid mixture comprising at least the first fluid component in an adsorptive separation system having a parallel passage adsorbent contactor with parallel flow passages having cell walls which include an adsorbent material. The method provides for transferring heat from the heat of adsorption in a countercurrent direction along at least a portion of the contactor during adsorption and transferring heat in either axial direction along the contactor and/or a direction transverse to the axial direction, to provide at least a portion of the heat of desorption during a desorption step. A carbon dioxide separation process to separate carbon dioxide from flue gas also includes steps transferring heat from adsorption or for desorption along the parallel passage adsorbent contactor.

1. RELATED APPLICATIONS

The present application is a continuation-in-part of previously filedU.S. patent application Ser. No. 14/543,765, filed Nov. 17, 2014 andentitled “Method of Adsorptive Gas Separation Using Thermally ConductiveContactor Structure”, which is a continuation of U.S. patent applicationSer. No. 13/819,319, filed Feb. 26, 2013 and entitled “Method ofAdsorptive Gas Separation Using Thermally Conductive ContactorStructure” and granted on Dec. 2, 2014 as U.S. Pat. No. 8,900,347, whichis a United States national stage application under 35 USC 371 ofpreviously filed PCT International Patent Application No.PCT/CA2011/050521, filed Aug. 26, 2011 and entitled “Method ofAdsorptive Gas Separation using Thermally Conductive ContactorStructure”, and which claims priority to previously filed U.S.Provisional Patent Application Ser. No. 61/377,875 filed Aug. 27, 2010and entitled “Method of Adsorptive Gas Separation using ThermallyConductive Contactor Structure”, the contents of each of which areherein incorporated by reference in their entirety.

2. TECHNICAL FIELD

The present invention relates generally to methods of adsorptive gasseparation and systems therefore. More particularly, the presentinvention relates to methods of adsorptive gas separation usingtemperature swing adsorption processes in a thermally conductiveparallel passage fluid contactor structure and systems incorporating thethermally conductive parallel passage fluid contactor structure.

3. BACKGROUND OF THE INVENTION

Temperature swing adsorption methods are known in the art for use inadsorptive separation of multi-component fluid mixtures, and gasmixtures in particular. Many conventional temperature swing adsorptionprocesses are used for preferentially adsorbing one component of a feedgas mixture on an adsorbent material to separate it from the remainingfeed gas components, and then subsequently to regenerate the adsorbentmaterial to desorb the adsorbed component and allow for cyclic reuse ofthe adsorbent material. However, conventional temperature swingadsorption methods are typically limited in their efficiency due in partto limitations in heat and/or mass transport phenomena in the desorptionor regeneration of the adsorbent material used in an adsorptiveseparation system, and also to limitations in the adsorption phase ofthe temperature swing adsorption process.

One shortcoming of typical conventional temperature adsorption processesis the inefficient adsorption of a feed gas component on the adsorbentmaterial, which may result from the rapid increase in temperature of theadsorption front when moving through the adsorbent material due to theheat of adsorption released as the gas component is adsorbed. In manyconventional temperature swing adsorption methods, such increases in thetemperature of the adsorbent material during adsorption may result indecreased adsorbent capacity associated with “hot spots” in theadsorbent material and a corresponding decrease in efficiency of thetemperature swing adsorption process. Another shortcoming of typicallyconventional temperatures swing adsorption methods is the inefficientdesorption or regeneration of the adsorbent material, which may resultfrom the difficulty in uniformly heating the adsorbent material asthermal energy is required to meet the heat of desorption of theadsorbed compound during desorption or regeneration. Suchnon-uniformities in the heating of the adsorbent material may typicallyresult in retained adsorption of a gas component associated with “coldspots” in the adsorbent material, or may require the application of anunnecessarily large thermal flux to sufficiently desorb the gascomponent, which may lead to undesirably high heating costs and leavethe adsorbent material unnecessarily overheated following desorption.

Further, conventional temperature swing adsorption methods typicallyemploy adsorbent contactor structures such as adsorbent beds forcontacting gas components with the adsorbent material. Exemplary knownadsorbent contactors include packed bead or parallel plate adsorbentstructures for adsorptive gas separation processes such as thermaland/or pressure swing adsorption processes, for example. However, someshortcomings of certain of the adsorbent contactors of the prior artrelate to poor hydrodynamic, mass transport, and thermal characteristicsof the contactor structure. In such cases, the poor thermalcharacteristics may undesirably result in either high thermal mass,which may require an undesirably large thermal energy flux to effect agiven temperature change in the structure, and/or lower than desiredthermal conductivity, which may result in undesirably large temperaturedifferences within the structure, for example. Such undesirable thermalcharacteristics of certain adsorbent contactors of the prior art maycontribute to some of the shortcomings of conventional temperature swingadsorption methods as described above. Aside from heat transportlimitations, the poor hydrodynamics of certain conventional temperatureswing adsorption structures may undesirably limit fluid throughput dueto fluidization limitations, as in the case of beaded adsorbent beds.Further, in certain conventional systems, undesirably low mass transferrates may limit the permissible cycle speed and also lower the dynamicselectivity of the cyclic adsorption-desorption process by limiting theadsorption selectivity of the system to only the adsorbent's inherentequilibrium selectivity, which may be undesirably low for separation ofa given fluid mixture.

4. SUMMARY OF THE INVENTION

It is an object of the present invention to provide a thermal swingadsorption separation method that addresses some of the limitations ofthe prior art.

It is a further object of the invention to provide a thermal swingadsorption separation method for separating first and second fluidcomponents of a fluid mixture using a parallel passage adsorbentcontactor structure according to the present invention that addressessome of the limitations of the prior art.

It is yet a further object of the invention to provide a thermal swingadsorption gas separation process for separating carbon dioxide from aflue gas feed mixture according to the present invention that addressessome of the limitations of the prior art.

In one embodiment of the present invention, a temperature swingadsorption method for separating a fluid mixture comprising at leastfirst and second fluid components is provided. The method comprisesfirst admitting the fluid mixture into an adsorptive separation systemcomprising at least one parallel passage adsorbent contactor, where theparallel passage adsorbent contactor comprises a plurality ofsubstantially parallel fluid flow passages oriented in a first axialdirection between an inlet and an outlet end thereof, cell wallssituated between the fluid flow passages comprising at least oneadsorbent material, and a plurality of axially continuous thermallyconductive filaments oriented in the axial direction and in directcontact with the at least one adsorbent material. Next, the methodcomprises admitting the fluid mixture into the inlet end of the parallelpassage adsorbent contactor to flow towards the outlet end in the firstaxial direction, adsorbing at least a portion of the first fluidcomponent on the at least one adsorbent material and transferring heatfrom a heat of adsorption of the first fluid component on the at leastone adsorbent material along at least a portion of the thermallyconductive filaments in a second axial direction towards the inlet endand opposite to the first axial direction during the adsorbing step.Next, the method comprises recovering a first product fluid depleted inthe first fluid component relative to the fluid mixture from the outletend. Following this, the method comprises desorbing at least a portionof the first fluid component adsorbed on the at least one adsorbentmaterial by heating the at least one adsorbent material, andtransferring heat along at least a portion of the thermally conductivefilaments in either of the first or second axial directions to provideat least a portion of the heat of desorption of the first fluidcomponent during the desorbing step. Finally, the method comprisesrecovering a desorbed second product fluid enriched in the first fluidcomponent from at least one of the inlet and outlet ends.

In an alternative embodiment of the present invention, the temperatureswing adsorption method additionally comprises admitting apre-regeneration fluid into said parallel passage adsorbent contactorand desorbing at least a portion of said second fluid componentco-adsorbed on said at least one adsorbent material by heating said atleast one adsorbent material to a pre-regeneration temperature, prior torecovering said first product fluid.

In yet a further embodiment, the at least one adsorbent material iskinetically selective for said first fluid component and has a firstmass transfer rate for said first fluid component which is greater thana second mass transfer rate for said second fluid component. In anoptional such embodiment, the temperature swing adsorption comprisesadmitting said fluid mixture into said inlet end of said parallelpassage adsorbent contactor at a space velocity greater than said secondmass transfer rate for said second fluid component and less than saidfirst mass transfer rate for said first fluid component

In another embodiment of the present invention, a temperature swingadsorption process for separating carbon dioxide from a flue gas feedmixture comprising at least carbon dioxide and nitrogen components isprovided. The process first comprises admitting the flue gas feedmixture, into an adsorptive separation system comprising at least oneparallel passage adsorbent contactor, where the parallel passageadsorbent contactor comprises a plurality of substantially parallelfluid flow passages oriented in a first axial direction between an inletand an outlet end thereof, cell walls situated between the fluid flowpassages comprising at least one carbon dioxide adsorbent material, anda plurality of axially continuous thermally conductive filamentsoriented in the axial direction and in direct contact with the at leastone carbon dioxide adsorbent material. Next, the process comprisesadmitting the flue gas into the inlet end of the parallel passageadsorbent contactor to flow towards the outlet end in the first axialdirection, and adsorbing at least a portion of the carbon dioxidecomponent on the at least one carbon dioxide adsorbent material. Next,the process comprises transferring heat from a heat of adsorption ofcarbon dioxide on the at least one carbon dioxide adsorbent materialalong at least a portion of the thermally conductive filaments in asecond axial direction towards the inlet end and opposite to the firstaxial direction during the adsorbing step, and recovering a flue gasproduct stream depleted in carbon dioxide relative to the flue gas feedmixture from the outlet end. Following this, the process comprisesdesorbing at least a portion of the carbon dioxide adsorbed on the atleast one carbon dioxide adsorbent material by heating the at least oneadsorbent material, and transferring heat along at least a portion ofthe thermally conductive filaments in either of the first or secondaxial directions to provide at least a portion of the heat of desorptionof the carbon dioxide during the desorbing step. Finally, the processcomprises recovering a desorbed carbon dioxide product enriched incarbon dioxide from at least one of the inlet and said outlet ends.

In yet a further embodiment of the present invention, a temperatureswing adsorption process for separating at least one of carbon dioxideand hydrogen sulfide from a natural gas feed mixture comprising at leastone of carbon dioxide and hydrogen sulfide and methane components isprovided. The process first comprises admitting the natural gas feedmixture into an adsorptive separation system comprising at least oneparallel passage adsorbent contactor, where the parallel passageadsorbent contactor comprises a plurality of substantially parallelfluid flow passages oriented in a first axial direction between an inletand an outlet end thereof, cell walls situated between the fluid flowpassages comprising at least one adsorbent material selective for atleast one of carbon dioxide and hydrogen sulfide over methane, and aplurality of axially continuous thermally conductive filaments orientedin the axial direction and in direct contact with the at least oneadsorbent material. Next the process comprises admitting the natural gasfeed mixture into the inlet end of the parallel passage adsorbentcontactor to flow towards the outlet end in the first axial direction,adsorbing at least a portion of at least one of the carbon dioxide andhydrogen sulfide components on the at least one adsorbent material, andtransferring heat from a heat of adsorption on the at least oneadsorbent material along at least a portion of the thermally conductivefilaments in a second axial direction towards the inlet end and oppositeto the first axial direction during the adsorbing step. Next, theprocess comprises recovering a natural gas product stream depleted in atleast one of carbon dioxide and hydrogen sulfide relative to the naturalgas feed mixture from the outlet end. Following this, the processcomprises desorbing at least a portion of at least one of carbon dioxideand hydrogen sulfide adsorbed on the at least one adsorbent material byheating the at least one adsorbent material, transferring heat along atleast a portion of the thermally conductive filaments in either of thefirst or second axial directions to provide at least a portion of theheat of desorption of carbon dioxide or hydrogen sulfide during thedesorbing step, and recovering a desorbed product enriched in at leastone of carbon dioxide and hydrogen sulfide from at least one of theinlet and outlet ends.

Further advantages of the invention will become apparent whenconsidering the drawings in conjunction with the detailed description.

5. BRIEF DESCRIPTION OF THE DRAWINGS

The methods of adsorptive gas separation of the present invention willnow be described with reference to the accompanying drawing figures, inwhich:

FIG. 1 illustrates a cross-sectional and corresponding inset perspectiveview of a parallel passage adsorbent contactor structure for use inaccordance with an embodiment of the present invention.

FIG. 2 illustrates a detailed cross-sectional perspective view of theparallel passage adsorbent contactor structure shown in FIG. 1 for usein accordance with an embodiment of the invention.

FIG. 3 illustrates an axial thermal profile graph of a parallel passageadsorbent contactor at the start of an adsorption step according to anembodiment of the present invention.

FIG. 4 illustrates an axial thermal profile graph of a parallel passageadsorbent contactor during an adsorption step according to an embodimentof the present invention.

FIG. 5 illustrates an axial thermal profile graph of a parallel passageadsorbent contactor at the conclusion of an adsorption step according toan embodiment of the present invention.

FIG. 6 illustrates an axial thermal profile graph of a parallel passageadsorbent contactor at the conclusion of a desorption or regenerationstep according to an embodiment of the present invention.

Like reference numerals refer to corresponding parts throughout theseveral views of the drawings.

6. DETAILED DESCRIPTION OF THE INVENTION

In one embodiment of the present invention, a temperature swingadsorption (hereinafter “TSA”) method is provided for separating a fluidmixture comprising at least first and second fluid components. In suchan embodiment, the TSA method may comprise an initial step of admittingthe fluid mixture or feed mixture, into an adsorptive separation systemwhich comprises at least one parallel passage adsorbent contactor. Inparticular, suitable such parallel passage adsorbent contactors maycomprise a plurality of substantially parallel fluid flow passagesoriented in a first axial direction between an inlet and outlet end ofthe contactor in order to permit fluid to flow through the contactor,and cell walls which comprise at least one adsorbent material situatedbetween and separating the fluid flow passages. The parallel passageadsorbent contactor may also desirably comprise a plurality of axiallycontinuous thermally conductive filaments oriented in the axialdirection of the contactor and in direct contact with the at least oneadsorbent material comprised in or on the cell walls of the contactor.The fluid mixture may then be admitted into the inlet end of theparallel passage adsorbent contactor to flow in a first axial directionthrough the contactor towards the outlet end, and at least a portion ofthe first fluid component may be adsorbed on the at least one adsorbentmaterial, which may preferably be selective for adsorbing the firstfluid component over other components of the fluid mixture. In analternative embodiment of the present invention, the parallel passageadsorbent contactor may comprise at least one axially thermallyconductive material such that the contactor is preferably thermallyconductive in the axial direction, and may be homogenous in thermalconductivity in the axial direction, or may have one or more axiallyoriented regions of higher axial thermal conductivity relative to therest of the contactor structure, for example.

In a further alternative embodiment, the parallel passage adsorbentcontactor may comprise at least one thermally conductive material suchthat the contactor is preferably thermally conductive in at least one ofan axial (i.e. substantially parallel to the axial dimension of theparallel fluid flow passages and direction of fluid flow through thecontactor) direction and a transverse direction (i.e. substantiallyperpendicular to the axial dimension of the parallel fluid flow passagesand direction of fluid flow through the contactor). In one suchalternative embodiment, the parallel passage adsorbent contactor maycomprise at least one thermally conductive material configuredsubstantially in a plane parallel in at least one direction to the axialdirection of the fluid flow passages and direction of fluid flow throughthe contactor, such that the parallel passage adsorbent contactor maydesirably be thermally conductive in at least axial and transversedirections along the plane, for example. In a particular suchembodiment, the parallel passage contactor may comprise at least onethermally conductive material configured such that the contactor isdesirably thermally conductive in either of an axial directionsubstantially parallel to the axial dimension of the contactor, or in atransverse direction substantially perpendicular to the axial dimensionof the contactor, for example.

In a preferred embodiment of the present invention, the at least oneadsorbent material comprised in the parallel passage adsorbent contactormay desirably be dynamically selective for adsorption of the first fluidcomponent over at least one other fluid mixture components, such that adynamic selectivity is sufficiently high to usably provide adsorptiveseparation of the fluid mixture by selective adsorption of the firstfluid component. Such dynamic selectivity over the cycle of the TSAseparation method may comprise at least one of an equilibriumselectivity of the at least one adsorbent material for the first fluidcomponent, and a kinetic selectivity of the at least one adsorbentmaterial for the first fluid component. In one such preferredembodiment, the feed mixture may be admitted to the adsorbent contactorat a space velocity (Vgas/Vads/t) less than the mass transfer rate (1/s)of the first fluid component to be selectively adsorbed, but greaterthan the mass transfer rate (1/s) of at least one second fluid componentwhich may be a diluent desired to be substantially prevented fromadsorption, such that the adsorption step may comprise at least akinetic selectivity based on the mass transfer rates of the fluidcomponents on the adsorbent material at the adsorbent temperature duringthe adsorption step.

In the present embodiment, at least a portion of the heat released fromthe heat of adsorption of the first fluid component on the at least oneadsorbent material is then transferred axially along the contactorstructure, such as along at least a portion of the thermally conductivefilaments in the adsorbent contactor in a second axial direction(opposite to the first axial direction) back along the contactor towardsthe inlet end of the contactor during the adsorption of the firstcomponent on the adsorbent material, such as to reduce a spike in thetemperature of the at least one adsorbent as adsorption of the firstfluid component occurs, and optionally also to desirably retain at leasta portion, such as to desirably retain a significant portion of the heatenergy released from the heat of adsorption within the adsorbentcontactor to allow recovery of such thermal energy during laterregeneration of the adsorbent material. A first product fluid depletedin the first fluid component relative to the feed fluid mixture is thenrecovered from the adsorbent contactor, such as from the outlet endthereof.

In an alternative embodiment, at least a portion of the heat releasedfrom the heat of adsorption of the first fluid component on the at leastone adsorbent material may then be transferred in at least one of anaxially and optionally also a transversely oriented direction relativeto the primary axial direction of the fluid flow through the adsorbentcontactor structure. In one such alternative embodiment, the adsorbentcontactor structure may comprise axially oriented thermally conductivefilaments, and also transversely oriented thermally conductivefilaments, such as transverse filaments oriented substantiallytransversely relative to the primary axial direction of fluid flowthrough the adsorbent contactor structure, and in a plane with theaxially oriented thermally conductive filaments. In one such alternativeembodiment, at least a portion of the heat released from the heat ofadsorption of the first fluid component on the at least one adsorbentmaterial may thereby be transferred in a first axial direction along theprimary axial direction of fluid flow in the adsorbent contactorstructure such as along at least a portion of axial thermally conductivefilaments, and also in a transverse direction relative to the firstaxial direction, such as along at least a portion of transverselyoriented thermally conductive filaments. In one such embodiment, theaxial and transverse thermally conductive filaments may be provided by asingle suitable conductive filament structure, such as a mesh, cloth, orother filament structure comprising both axial and transversely orientedthermally conductive filaments, for example.

In one embodiment, an intermediate recycle or pre-regeneration step maybe performed in order to desirably desorb at least a portion of any ofthe second fluid component or other diluent fluid components which maybe undesirably co-adsorbed on the at least one adsorbent material alongwith the adsorbed first fluid component (such undesired second and/ordiluent fluid components may have become adsorbed on the adsorbentmaterial during a previous cooling or conditioning step, or during thefeed adsorption step due to incomplete selectivity of the adsorbentmaterial, for example) and thereby increase the dynamic selectivity ofthe process for separation of the first fluid component from the secondand/or any other diluent fluid components. Such an intermediatepre-regeneration step may be particularly desirable for use inseparations where the first fluid component of the feed fluid mixture isrelatively dilute, such as at first component feed concentrations belowabout 10% and even more preferably below about 5%, for example. Such anintermediate pre-regeneration step may desirably be conducted at anintermediate temperature above the temperature of the adsorption or feedstep, but below the temperature of the following desorption orregeneration step. In one such embodiment, heat may be provided for suchpre-regeneration step by one or more means, such as: providing a purgefluid at an intermediate temperature and providing heat to the adsorbentmaterial by means of the thermally conductive filaments in the adsorbentcontactor, for example. In one particular such embodiment, a heatedpurge fluid enriched in the first component may be used as a suitablepurge fluid, such that at least a portion of any adsorbed second ordiluent fluid components adsorbed on the adsorbent material are desorbedat an intermediate temperature and displaced by additional adsorption offirst fluid component from the heated purge fluid onto the adsorbentmaterial, such that the adsorbed fluid species desirably comprises onlythe first fluid component.

In an optional embodiment, during a pre-regeneration step, at least aportion of the heat of adsorption generated during the adsorption stepmay optionally be transferred in either a first or second (opposite tothe first) axial direction along at least a portion of the thermallyconductive filaments of the adsorbent contactor structure, such as toprovide at least a portion of the heat of desorption (energy requiredfor adsorption to overcome the adsorptive bond of the adsorbed fluidspecies to the adsorbent) and/or kinetic activation heat (energyrequired for transferring adsorbed second component molecules from theadsorptive surface of the adsorbent to the gas phase) of the secondfluid component from the at least one adsorbent material during thepre-regeneration step. In another optional embodiment, a purge fluid mayoptionally be admitted, such as from the outlet end, into the parallelpassage adsorbent contactor such as to flow in substantially the secondaxial direction (opposite to the first axial direction) through theadsorbent contactor towards the inlet end (or optionally in anotherdirection substantially opposite to the direction of flow of fluidmixture or feed mixture through the adsorbent contactor during theadsorption step), which may desirably retain and employ at least aportion of the heat of adsorption of the first component to provide atleast a portion of the required heat of desorption during thepre-regeneration step and for desorption of the first component, secondcomponent, and/or other co-adsorbed components, adsorbed on the at leastone adsorbent material. In one such embodiment, a resulting reflux fluidmay be recovered from adsorbent contactor, such as from the inlet endthereof.

In one embodiment, following such an intermediate recycle orpre-regeneration step, the resulting purge fluid exiting the adsorbentcontactor may be recycled such as for supply as a reflux stream toeither the inlet or outlet end of an adsorbent contactor (may be abottom to bottom or “heavy” reflux stream supplied to the inlet or heavyend of the adsorbent contactor in a subsequent cycle for example) oralternatively may be recycled into the feed fluid for admitting to theadsorbent contactor in a subsequent feed step. In one such preferredembodiment, the purge fluid may be supplied to the adsorbent contactorin such a pre-regeneration step at a suitable temperature and spacevolume (Vgas/Vads/t) greater than the mass transfer rate (1/s) for thedesorption of undesired adsorbed second or diluent component fluid, butdesirably less than the mass transfer rate (1/s) for desorption ofadsorbed first fluid component adsorbed on the adsorbent material.

Following such recovery of the first product fluid and optionally alsosuch pre-regeneration purge step, at least a portion of the first fluidcomponent adsorbed on the at least one adsorbent material is thendesorbed by heating the at least one adsorbent material, and heat istransferred in either axial direction along at least a portion of thethermally conductive filaments of the adsorbent contactor to provide atleast a portion of the heat of desorption (energy required fordesorption) and/or kinetic activation heat (energy required fortransferring adsorbed first component molecules from adsorptive surfaceto the gas phase) of the first fluid component from the at least oneadsorbent material during the desorption step. Heating of the adsorbentmaterial may be provided by supplying heat from at least one heatsource, including, but not limited to: providing a heated desorption orpurge fluid to the adsorbent contactor which may comprise a heated inertgas, recycle gas, and/or condensable gas such as steam or solvent; andheating thermally conductive filaments or other materials in theadsorbent contactor structure, such as by electrical resistive heatingof conductive filaments, or indirect heating of such filaments orstructure materials such as with a heat transfer medium. Finally, adesorbed second product fluid enriched in the first fluid componentdesorbed from the adsorbent material is recovered from at least one ofthe inlet and outlet ends of the parallel passage adsorbent contactor.In one embodiment of the invention where a condensable purge fluid isused to provide at least a portion of the heating of the adsorbentmaterial in the desorption step, the recovered product fluid maysubsequently be cooled to condense the purge fluid (such as steam orsolvent, for example) for removal from the desorbed product fluid,thereby allowing for increased purity of the desorbed product fluid, forexample. In one such embodiment, a heated desorption or purge fluid maybe admitted to the parallel passage adsorbent contactor to flow in atleast one of the first axial direction (i.e. the same direction as thefeed fluid during the adsorption step) and the second axial direction(i.e. opposite to the direction of the feed fluid during adsorptionstep) so as to provide at least a portion of the heat of desorptionand/or kinetic activation heat required during desorption.

The present TSA separation method according to the above embodiment maythen optionally be repeated in the parallel passage adsorbent contactorto provide for a continuous or repeated cyclic separation method forseparating a first fluid component from the feed fluid mixture. Inparticular, an adsorptive separation system for operation according tothe present TSA separation method may desirably comprise two or moresuch parallel passage adsorbent contactors, so as to provide forstaggered operation of the present TSA separation method and allowcontinuous and/or semi-continuous adsorptive separation from a source offeed fluid. In particular, an adsorptive separation system may comprisetwo or more parallel passage adsorbent contactors such that the firstproduct fluid may be recovered from one contactor while the desorbedsecond product fluid is recovered from the second contactor. Anysuitable mechanical arrangement may be implemented in the adsorptiveseparation system to provide for and control the fluid flows requiredfor implementation of the TSA method of the present embodiment, such asan adsorptive separation system using mechanical/pneumatic or othertypes of valves or other flow control devices for example to implementthe fluid flows of the steps of the present TSA method, as are known inthe art for systems comprising one, two, or three or more adsorberscontaining adsorbent material.

In one embodiment of the present invention, an adsorptive separationsystem suitable for implementing the present inventive TSA methodcomprises at least one parallel passage adsorbent contactor which eachcomprise a plurality of substantially parallel fluid flow passagesoriented in a first axial direction between and inlet and outlet end ofthe contactor in order to permit fluid to flow through the contactor,and cell walls which comprise at least one adsorbent material situatedbetween and separating the fluid flow passages. Each suitable suchparallel passage adsorbent contactor further comprises a plurality ofaxially continuous thermally conductive filaments oriented in the axialdirection of the contactor and in direct contact with the at least oneadsorbent material comprised in or on the cell walls of the contactor.Certain such parallel passage adsorbent contactor structures which maybe suitable for use in implementing the TSA method according to anembodiment of the present invention are described in the applicant'sco-pending PCT international patent application filed asPCT/CA2010/000251 on Feb. 26, 2010, the contents of which are hereinincorporated by reference as though they had formed part of thisapplication as presently filed. One particular parallel passageadsorbent contactor configuration suitable for implementation of the TSAmethod according to an embodiment of the present invention is shown inFIGS. 1 and 2 and described in further detail below.

FIG. 1 illustrates an exemplary parallel passage adsorbent contactorstructure suitable for implementing the present TSA method according toan embodiment of the invention. The exemplary parallel passage adsorbentcontactor structure indicated generally at 102 comprises a substantiallycylindrical shape defined by substantially cylindrical outer surface108. The exemplary contactor structure 102 is shown with first andsecond ends 104 and 106, with multiple substantially parallel passages110 extending axially along the length of the structure 102, from thefirst end 104 to the second end 106. The parallel passages 110 arepreferably continuous along the length of the structure 102 and areadapted to allow the flow of fluid through the passages 110. Parallelpassages 110 are separated from each other by cell walls 112 to form anexemplary honeycomb structure wherein each passage 110 is substantiallyseparated from adjacent passages 110 by at least one cell wall 112 whichdesirably comprises at least one adsorbent material. Parallel passageadsorbent contactor structure 102 also comprises axially continuousthermally conductive filaments 114 embedded in or otherwise situatedwithin cell walls 112, in order to provide at least thermal andoptionally also electrical conductivity for the parallel passageadsorbent contactor structure 102 in either axial direction. In oneembodiment, the parallel passage adsorbent contactor structure 102 maybe a substantially honeycomb structure, as illustrated in FIG. 1,wherein cell walls 112 are substantially arranged in a grid pattern,such as a rectangular grid as shown in FIG. 1, or alternatively, as ahexagonal or other substantially polygonal, circular or oval grid. It isto be understood that for the purposes of the present description theterm “axial” and “axial direction” with respect to the contactorstructure encompasses both the directions that are substantiallyparallel to a line between the first and second ends (or inlet andoutlet ends) of a contactor structure, and also any direction thatextends in a substantially axial fashion with regard to the contactor,such as directions that are substantially less than 45 degrees from aline between the first and second ends, for example.

Similarly, FIG. 2 illustrates a detailed cross-sectional perspectiveview of the parallel passage adsorbent contactor structure shown in FIG.1, having a substantially rectangular grid honeycomb structure, suitablefor implementing the present TSA method according to an embodiment ofthe invention. In such a rectangular grid honeycomb structure 102 asshown in FIGS. 1 and 2, axially continuous and thermally and/orelectrically conductive filaments 114 are in direct contact with thecell walls 112 which comprise at least one adsorbent material, and mayadvantageously be embedded in or otherwise situated within cell walls112 at the intersection of two cell walls 112, which correspondsgenerally with a corner of each adjacent parallel passage 110. In such amanner, the axially continuous and thermally and/or electricallyconductive filaments 114 may be advantageously located proximate tomultiple adjoining parallel passages 110, such that the thermal and/orelectrical conductivity capacity provided by the filaments 114 is inclose proximity to multiple parallel passages 110 and to the fluid thatmay be contained in or passed through such parallel passages 110 duringuse of the parallel passage adsorbent contactor. In alternativeembodiments, honeycomb structures with cell walls 112 arranged inalternative geometric arrangements may be utilized, for example havingcell walls in a hexagonal, triangular, or other polygonal gridarrangement, resulting in substantially similarly shaped parallel fluidflow passages 110. Further, other embodiments may comprise parallelpassages 110 with cross sectional shapes other than polygons, such ascircular, semi-circular, oval, or obround (a shape with two semicirclesconnected by parallel lines connecting their endpoints) cross-sections,for example. Also, in other alternative embodiments, axially continuousconductive filaments 114 may be embedded in or otherwise located withincell walls 112 either at the intersections of cell walls 112, or atother locations, such as within cell walls 112 between suchintersections for example.

In the honeycomb parallel passage adsorbent contactor 102 as illustratedin FIGS. 1 and 2, and in other alternative embodiments as describedabove, axially continuous and thermally and/or electrically conductivefilaments 114 may desirably be used to conduct thermal energy (either assensible thermal energy or as thermal energy resulting from electricalresistance heating of the filaments) into or out of the contactor 102 oraxially from one portion of the contactor structure 102 to another, andaccordingly to provide for respective heating and/or cooling of portionsof or the entire contactor 102. In particular, at least a portion of theaxially continuous thermally and/or electrically conductive filaments114 of contactor 102 may desirably be thermally connected to a source orsink of thermal energy, in order to conduct thermal energy into or outof the contactor structure 102. Such thermal energy conducted into orout of the contactor 102 may desirably increase or decrease thetemperature of the contactor 102, such as cell walls 112 comprising theat least one adsorbent material, and/or may transfer thermal energy intoor out of a fluid within the passages 110 of the adsorbent contactorstructure 102. Exemplary thermal circuits comprising connections ofthermally and/or electrically conductive filaments 114 of the adsorbentcontactor structure 102 to controllable heat sources and/or heat sinksmay be employed to provide controllable heating and cooling of the cellwalls 112 of the structure and the adsorbent material(s) comprisedtherein through transfer of thermal energy into and/or out of thecontactor structure 102 via the conductive filaments 114, allowing forthermal control of the contactor 102 or a fluid passed through thecontactor 102 via an exemplary thermal and/or electrical circuitconnected to the conductive filaments 114. Further, axially continuousthermally and/or electrically conductive filaments 114 also provide forthe transfer of thermal energy in either a first or second axialdirection within the contactor structure 102 itself, such as from thefirst end 104 of the contactor 102 to the second end 106, which may beparticularly desirable to provide control of a thermal profile along theaxial length of the contactor 102, for example. In such a manner,embodiments of the present TSA method according to the present inventionmay desirably transfer heat in either axial direction along the parallelpassage adsorbent contactor 102 to control thermal conditions andprofile within the parallel passage adsorbent contactor 102 that areindependent of the temperature of a fluid flowing into or out of thecontactor structure 102, by means of transferring thermal energy withinthe contactor structure 102 (and optionally also into or out of thecontactor structure 102), through the axially continuous conductivefilaments 114.

The parallel passage adsorbent contactor structures as described abovefor use in implementing the present TSA methods according to anembodiment of the present invention may comprise anisotropic thermalconductivity in the axial direction relative to the transversedirection, due to the provision of substantially increased thermalconductivity in the axial direction by the axially continuous thermallyconductive filaments, relative to the thermal conductivity of thestructure in the transverse direction. In one such embodiment, suchparallel passage adsorbent contactor structures may comprise anisotropicthermal conductivity where the thermal conductivity in the axialdirection is at least 10 times, and more particularly at least 100 timesthe thermal conductivity of the structure in the transverse direction,due to the axial thermal conductivity capacity provided by the axiallycontinuous thermally conductive filaments included in the structure. Inan alternative embodiment of the present invention, the parallel passageadsorbent contactor may comprise at least one axially thermallyconductive material such that the contactor is preferably thermallyconductive in the axial direction, and may be homogenous in thermalconductivity in the axial direction, or may have one or more axiallyoriented regions of higher axial thermal conductivity relative to therest of the contactor structure which may or may not comprise discreteconductive filaments, for example.

In another alternative embodiment of the present invention, a parallelpassage adsorbent contactor structure for use in implementing thepresent TSA methods according to an embodiment of the present inventionmay comprise substantially isotropic thermal conductivity in the axialdirection and transverse direction or along a substantial plane(parallel to the axial direction), for example, substantially parallelto the parallel passages or the adsorbent contactor or first axialdirection, such as by employing axially and optionally also transverselyoriented continuous or substantially continuous thermally and/orelectrically conductive filaments. Any suitable known thermally and/orelectrically conductive filament materials (for example, metal, metalalloys, carbon, graphite, or carbon nano-fibers) may be drawn, shaped,formed or otherwise fashioned into continuous filaments or substantiallycontinuous filaments extending in axial and optionally also transversedirections such as spaced filaments, mesh, mats, or fabric, for example.

In a particular embodiment suitable for implementing the present TSAmethods, the parallel passage adsorbent contactor structure 102 maycomprise an adsorbent compound that is operable to interact with a fluidmixture passed through the passages 110 of the parallel passageadsorbent contactor 102. For example, the cell walls 112 of thecontactor 102 may comprise at least one adsorbent compound that isselected to adsorb a first fluid component of the fluid mixture admittedthrough the parallel fluid flow passages 110 and in contact with thecell walls 112 of the contactor. In such embodiments, the thermallyand/or electrically conductive filaments 114 within the cell walls 112may advantageously provide for transferring thermal energy into and/orout of the adsorbent structure 102, such as to enable the use of theadsorbent structure 102 in the adsorptive separation system to implementthe TSA methods of the present invention, whereby the active adsorbentmaterial in the cell walls 112 may be heated by the thermally and/orelectrically conductive filaments 114 to raise the temperature of theadsorbent material, such as during a desorption step, and thereby todesorb at least a portion of an adsorbed fluid component. In suchembodiment, any suitable known adsorbent compounds, or combinationsthereof, which may be desirably selected in order to adsorb a desiredfirst component of the feed fluid mixture may be comprised in or on thecell walls 112 of the contactor.

In a further such embodiment, any suitable active adsorbent compoundknown to be operable to adsorb at least a portion of the first fluidcomponent of the feed fluid mixture admitted through the passages 110 ofparallel passage adsorbent contactor structure 102, may be comprised inor on the cell walls 112 of the structure. Exemplary such knownadsorbent compounds may comprise, but are not limited to: desiccant,activated carbon, carbon molecular sieve, carbon adsorbent, graphite,activated alumina, molecular sieve, aluminophosphate,silicoaluminophosphate, zeolite adsorbent, ion exchanged zeolite,hydrophilic zeolite, hydrophobic zeolite, modified zeolite, naturalzeolites, faujasite, clinoptilolite, mordenite, metal-exchangedsilico-aluminophosphate, uni-polar resin, bi-polar resin, aromaticcross-linked polystyrenic matrix, brominated aromatic matrix,methacrylic ester copolymer, graphitic adsorbent, carbon fiber, carbonnanotube, nano-materials, metal salt adsorbent, perchlorate, oxalate,alkaline earth metal particle, ETS, CTS, metal oxide, chemisorbent,amine, organo-metallic reactant, hydrotalcite, silicalite, zeoliticimadazolate framework and metal organic framework (MOF) adsorbentcompounds, and combinations thereof. In a preferred embodiment of thepresent invention, such suitable active adsorbent compound may desirablybe selected so as to provide sufficiently high dynamic selectivity(which may comprise at least one of equilibrium and/or kineticselectivity) for a first fluid component over a second fluid componentover the cyclic TSA process.

In yet a further embodiment, the honeycomb parallel passage adsorbentcontactor structure 102 shown in FIG. 1 may comprise an extrudedhoneycomb structure such as may be made by the extrusion of a ceramic orother composite slurry material through a die. In such a case, themultiple parallel passages 110 extending through the parallel passagefluid contactor structure 102 and the cell walls 112 separating adjacentpassages 110 may be formed by the shape of an exemplary extrusion die,such as by an extrusion die comprising multiple spaced apart pin or roddie elements, through which a ceramic or other composite slurry may beextruded to form the structure 102. In such an embodiment, said ceramicor other composite slurry may comprise at least one inactive orstructural material such as a binder material, for example, in additionto the at least one adsorbent material operable to interact with a fluidpassed through passages 110 of structure 102, for example. In otherembodiments, said inactive or structural material may comprise at leastone of a clay, ceramic, colloid, silica, adhesive, resin, and bindercompound, or combinations thereof.

According to an embodiment suitable for use in implementing the TSAmethods according to embodiments of the invention, axially continuousthermally and/or electrically conductive filaments 114 may comprise anysuitable known thermally and/or electrically conductive materials whichmay be drawn, shaped, formed or otherwise fashioned into a continuousfilament 114. In a preferred embodiment, filaments 114 may comprise oneor more materials having a desirably high thermal conductivity, in orderto enable efficient conduction of thermal energy into or out of the cellwalls 112 of parallel passage fluid contactor structure 102, withincontactor 102 in the axial direction, and/or into or out of fluidpassing through the passages 110 of contactor 102. In an optionalembodiment, substantially continuous filaments oriented in a transversedirection may also be employed such as to enable conduction of thermalenergy in a transverse direction (relative to the axial direction, suchas in a transverse direction along a plane substantially parallel to theaxial direction). Exemplary such known thermally conductive materialsmay comprise, but are not limited to, aluminum, copper, tungsten,silver, gold and metallic alloys thereof, as well as carbon, and carbonfiber and nano-fiber materials. Advantageously, the axially continuousconductive filaments 114 in suitable contactor structures 102 may beformed from suitable known materials having an axial thermalconductivity of at least 200 W/mK, and more preferably at least about400 W/mK, in order to provide filaments 114 capable of efficientlyconducting thermal energy into, out of, or within the contactorstructure 102. In a particular embodiment, the axially continuousthermally and/or electrically conductive filaments 114 may comprise athermally conductive carbon material comprising one or more of aphenolic resin carbon fiber, a mesophase carbon fiber, and a carbonnanotube material, wherein the carbon material has an axial thermalconductivity of at least 400 W/mK, and more preferably at least about500 W/mK. In a further embodiment, the type of material and relativedimensions and spacing of the axially continuous thermally and/orelectrically conductive filaments 114 may be selected so as to provide abulk axial thermal conductivity of the entire parallel passage adsorbentcontactor structure of at least 0.25 W/mK, and more particularly of atleast about 1 W/mK. In yet a further exemplary embodiment, the type ofmaterial and relative dimensions and spacing of the axially continuousthermally and/or electrically conductive filaments 114 may be selectedso as to provide a bulk axial thermal conductivity of the entireparallel passage fluid contactor structure of at least about 10 W/mK. Inone exemplary embodiment where the parallel passage adsorbent contactorstructure comprises a void fraction of about 35% and comprisesconductive filaments with an axial thermal conductivity of about 600W/mK, the structure may desirably comprise a bulk axial thermalconductivity of at least about 10 W/mK and more desirably at least about20 W/mK, for example.

In yet another embodiment, the axially continuous thermally conductivefilaments 114 running axially within contactor structure 102 may also beelectrically conductive. Preferably, such electrically conductivefilaments 114 may be resistively heated upon passing an electricalcurrent through the filaments 114 in an axial direction. Therefore,electrically conductive filaments may be controllably heated or cooledby connecting the electrically conductive filaments to an electricalcircuit, and controlling the passage of an electric current through thefilaments to increase and/or decrease the relative temperature of thefilaments 114 by means of resistive heating, such as to implementdesorption steps of the present inventive TSA methods, for example. Thisin turn provides for electrical control of heating and/or cooling of thecell walls 112 of the parallel passage fluid contactor structure 102that are in direct contact with the filaments 114, and in turn alsoprovides for electrical control of heating and/or cooling of the one ormore active adsorbent compounds comprised in or on the cell walls 112 ofthe structure 102. Accordingly, in such an embodiment, control ofelectrical current flowing through the filaments 114 of the structure102 may be used to control heating and cooling of the adsorbent materialin or on the cell walls 112 of the structure.

Additionally, it should be noted that for all embodiments describedabove for use in adsorptive separation systems for implementing the TSAmethods according to embodiments of the present invention, the relativedimensions of the parallel fluid flow passages 110, cell walls 112 andaxially continuous thermally conductive filaments 114 may be adapted tosuit the desired characteristics of the contactor structure 102 for anydesired application or use, such as desired characteristics for fluidflow including pressure drop, characteristics for structural integrityand strength, porosity and/or void ratio for the structure 102, thermalcapacity and/or mass of the structure, and axial thermal conductivityprovided by filaments 114 for example, among other potentially desiredcharacteristics.

In an alternative embodiment of the present invention, a parallelpassage adsorbent contactor in the adsorptive separation system maycomprise axially thermally conductive means other than axiallycontinuous thermally conductive filaments. In such alternativeembodiment, such axially thermally conductive means may comprisediscontinuous or randomly oriented thermally conductive elements and/oran axially thermally conductive adsorbent material, for example, whichmay be operable to transfer heat in a substantially axial direction inthe adsorbent contactor structure. In such an alternative embodiment,the present TSA method may then alternatively comprise the step oftransferring heat from the heat of adsorption along at least a portionof the alternative axially thermally conductive means in acountercurrent second axial direction which is substantially opposite tothe first axial direction of feed fluid being admitted to the adsorbentcontactor during the adsorption step. Such alternative embodiment of theTSA method may also comprise the step of transferring heat insubstantially either axial direction along at least a portion of thealternative axially thermally conductive means to provide at least aportion of the heat of desorption during the desorption step, forexample.

FIG. 3 illustrates an axial thermal profile graph 300 of a parallelpassage adsorbent contactor at the start of an adsorption step accordingto an embodiment of the present invention, showing a plot 320 of thetemperature of an adsorbent material in the adsorbent contactor alongthe axial dimension 302 of the parallel passage adsorbent contactor fromthe inlet end 304 to the outlet end 306, against the temperature scale308 of the adsorbent contactor from a lower temperature bound T1 310 toan upper temperature bound T2 312. In the exemplary plot 320, the feedfluid mixture is admitted in a first axial direction 314 flowing fromthe inlet end 304 towards the outlet end 306 of the parallel passageadsorbent contactor. The temperature of the parallel passage adsorbentcontactor at the start of adsorption has begun to rise at the inlet end304 to reach temperature 322, due to the heat of adsorption released asa first fluid component begins to be adsorbed on the adsorbent materialat the leading edge of the thermal front (which together with the masstransfer front comprise the adsorptive front) during the adsorption stepof the present TSA method according to an embodiment of the invention.Accordingly, the lowest temperature of the contactor is shown at 328which is slightly upstream of the inlet end 304. During the adsorptionstep, heat from the heat of adsorption of the first fluid component onat least one adsorbent material in or on the cell walls of the contactorcreates a thermal spike in the parallel passage adsorbent contactorwhich may undesirably tend to raise the temperature of the adsorbentmaterial and may reduce the adsorptive capacity and hence theeffectiveness of the adsorbent material for removing the first fluidcomponent from the feed fluid mixture. A portion of the heat from theheat of adsorption of the first fluid component may be transferred alongthe contactor towards the outlet end 306 by the effect of convection 316within the contactor due to the movement of the fluid mixture admittedto the contactor and moving towards the outlet end 306. However, thisconvection effect 316 may only be effective to transfer heat in the samefirst axial direction of fluid flow 314 and therefore may act only toincrease the temperature of the contactor and adsorbent material towardsthe outlet end 306.

Accordingly, an embodiment of the present TSA method provides for thetransfer of heat from the heat of adsorption of the first fluidcomponent on the adsorbent material in the parallel passage adsorbentcontactor along at least a portion of the thermally conductive filamentsin the contactor in a second axial direction 318 towards the inlet end304 of the contactor and opposite to the first axial direction of flowof the feed fluid 314 and corresponding convective heat movement 316through the adsorbent contactor. Such transfer of heat in the secondaxial direction 318 by conduction along at least a portion of thethermally conductive filaments in the contactor, and opposite orcountercurrent to the flow of feed fluid through the contactor mayadvantageously reduce the thermal spike in the temperature of thecontactor and adsorbent material created by the heat of adsorption asthe adsorptive front moves in the first axial direction 314 from theinlet end 304 towards the outlet end 306 of the adsorbent contactor,thereby desirably increasing the adsorptive capacity and hence theeffectiveness of the adsorbent material. Further, such countercurrentheat transfer 318 by conduction along at least a portion of thermallyconductive filaments in the parallel passage adsorbent contactor mayalso desirably reduce the amount of thermal energy or heat which may beswept along by convection 316 with the flow of the feed fluid 314through the contactor and removed from the contactor when the firstproduct fluid leaves the outlet end 306 of the contactor, which wouldotherwise undesirably increase the required thermal energy or heatrequired for desorption (including heat of desorption and/or kineticactivation) of the first fluid component from the adsorbent materialduring a desorption or regeneration step.

FIG. 4 illustrates an axial thermal profile graph 400 of a parallelpassage adsorbent contactor during an adsorption step according to anembodiment of the present invention showing a plot 420 of thetemperature of an adsorbent material in the adsorbent contactor alongthe axial dimension 302 of the parallel passage adsorbent contactor fromthe inlet end 304 to the outlet end 306, against the temperature scale308 of the adsorbent contactor from a lower temperature bound T1 310 toan upper temperature bound T2 312. In the exemplary plot 420, the feedfluid mixture is being admitted to the contactor in a first axialdirection 414 flowing from the inlet end 304 towards the outlet end 306of the parallel passage adsorbent contactor to be recovered as the firstproduct fluid depleted in the first fluid component, and the leadingedge of the adsorptive front 422 has moved axially along the contactorduring the adsorption step. The temperature of the parallel passageadsorbent contactor at the leading edge of the thermal front 422 (whichalong with the mass transfer front comprise the adsorptive front movingthrough the contactor during adsorption) is higher than at the inlet endof the parallel passage adsorbent contactor 426 as a portion of the heatof adsorption has moved under convection 416 in the first axialdirection co-current with the flow of feed fluid mixture 414. However,as provided in the present embodiment of the inventive TSA method, heatfrom the heat of adsorption of the first fluid component on theadsorbent material is transferred in the second axial direction 424countercurrent to the flow 414 of feed fluid mixture by conduction alongat least a portion of the thermally conductive filaments of the parallelpassage adsorbent contactor structure. Such countercurrent heat transferby conduction is evident in the flow of heat 424 near the inlet end 304of the contactor near the advancing adsorption front, as well as in thecountercurrent flow of heat 418 towards the coolest point of thecontactor 428 by conduction along at least a portion of the thermallyconductive filaments of the contactor, thereby providing for desirablyimproved retention of the heat or thermal energy from the heat ofadsorption of the first fluid component within the contactor. Since themass transfer front component of the adsorptive front may typically lagbehind the thermal front as adsorption proceeds through the contactor,such countercurrent conduction of heat 418 along at least a portion ofthe thermally conductive filaments of the contactor may alsoadvantageously allow for progression of the mass transfer front furtherthrough the adsorbent contactor towards the outlet end 306 whilesubstantially retaining heat from the thermal front (originating fromthe heat of adsorption) within the adsorbent contactor, and maytherefore desirably increase utilization of the adsorptive capacity ofthe adsorbent contactor during adsorption, increasing efficiency of theTSA method.

FIG. 5 illustrates an axial thermal profile graph 500 of a parallelpassage adsorbent contactor at the conclusion of an adsorption stepaccording to an embodiment of the present invention and the beginning ofa desorption step, showing a plot 520 of the temperature of an adsorbentmaterial in the adsorbent contactor along the axial dimension 302 of theparallel passage adsorbent contactor from the inlet end 304 to theoutlet end 306, against the temperature scale 308 of the adsorbentcontactor from a lower temperature bound T1 310 to an upper temperaturebound T2 312. In the exemplary plot 520, the feed fluid mixture is nolonger being admitted to the contactor, the first product fluid depletedin the first fluid component is no longer being recovered from theoutlet end 306, and a desorption or purge fluid flow 530 is now admittedto the contactor flowing from the outlet end 306 towards the inlet end304 of the parallel passage adsorbent contactor in the second axialdirection. The leading edge of the desorption front 528 is just enteringthe outlet end 306 of the contactor and will be moving axially along thecontactor towards the inlet end 304 during the desorption step. Thehighest temperature 520 of the parallel passage adsorbent contactor isat the outlet end and decreases towards the edge of the desorption front528 due to the heat of desorption required to desorb the first fluidcomponent from the adsorbent material during the desorption step.Desirably, an embodiment of the present TSA method provides for transferof heat by conduction along at least a portion of the axial thermallyconductive filaments in the parallel passage adsorbent contactor toprovide at least a portion of the heat of desorption and/or kineticactivation required to desorb the first fluid component from theadsorbent material. Such transfer of heat 518 by conduction along theconductive filaments of the contactor is shown in FIG. 5 in the secondaxial direction or co-current with the flow of desorption or purge fluid530 towards the inlet end 304 of the contactor. As the desorption frontpasses through the contactor towards the inlet end 304, the conductivetransfer of heat along at least a portion of the thermally conductivefilaments of the contactor may be provided in either the first or secondaxial directions, i.e. co-current or countercurrent to the flow ofdesorption or purge fluid 530, in order to provide at least a portion ofthe heat of desorption required to desorb the first fluid component fromthe adsorbent material. Such heat transfer may also desirably reduce anythermal dip or spike in the temperature of the adsorbent material in thecontactor due to the heat of desorption, thereby increasing theeffectiveness of the desorption from the adsorbent material andcorrespondingly increase the capacity of the adsorbent material forsubsequent adsorption cycles. In an alternative embodiment including apre-regeneration purge step as described above, at least a portion ofthe heat of desorption and/or kinetic activation for an undesiredadsorbed second or diluent fluid component adsorbed on the adsorbentmaterial during such pre-regeneration step may also be provided byconductive heat transfer along the thermally conductive filaments of thecontactor, for example.

FIG. 6 illustrates an axial thermal profile graph of a parallel passageadsorbent contactor at the conclusion of a desorption or regenerationstep according to an embodiment of the present invention showing a plot620 of the temperature of an adsorbent material in the adsorbentcontactor along at least a portion of the axial dimension 302 of theparallel passage adsorbent contactor from the inlet end 304 to theoutlet end 306, against the temperature scale 308 of the adsorbentcontactor from a lower temperature bound T1 310 to an upper temperaturebound T2 312. In the exemplary plot 620, the desorption or purge fluidis no longer being admitted to the contactor and the desorbed productfluid enriched in the first fluid component is no longer being recoveredfrom the inlet end 304, and in one embodiment the contactor may be readyto begin admitting the feed fluid mixture and resuming the adsorptionstep of the present TSA method. In an alternative embodiment, aconditioning fluid flow 614 may be admitted to the contactor flowingfrom the inlet end 304 towards the outlet end 306 of the parallelpassage adsorbent contactor in the first axial direction, such as tochange the temperature of the adsorbent material in the contactor, or todesorb or sweep other fluid components from the contactor prior tobeginning the adsorption step of the present TSA method. In oneembodiment, the conditioning fluid flow 614 may be admitted to thecontactor to lower the temperature of the adsorbent material prior toadsorption, or to dehumidify or otherwise condition the adsorbentmaterial. During such an optional conditioning step, one embodiment ofthe present TSA method may provide for heat transfer 616 in the firstaxial direction along the parallel passage adsorbent contactor by meansof convection co-current with the flow of conditioning fluid 614. In analternative embodiment, heat transfer by conduction along at least aportion of the thermally conductive filaments of the contactor may alsobe provided, which may transfer heat in either the first or second axialdirection such as to desirably reduce variations in the temperature ofthe adsorbent material in the contactor prior to adsorption. Followingthe end of the desorption or regeneration step (or conditioning step inthe case of an alternative embodiment) the highest temperature 620 ofthe parallel passage adsorbent contactor is at the outlet end anddecreases towards the lowest temperature 628 nearest the inlet end 304of the contactor, in preparation for resumption of the adsorption stepof the present TSA method.

In one embodiment of the present invention, adsorption of the firstfluid component on the at least one adsorbent material may take place ata first adsorbent material temperature, or a first range of adsorbentmaterial temperatures over the thermal profile of the parallel passageadsorbent contactor, which differs from a second adsorbent materialtemperature or range of adsorbent material temperatures at whichdesorption of the first fluid component takes place during a desorbingstep. In such an embodiment the adsorbent material may typically beheated to desorb the first fluid component, and therefore the secondtemperature at which desorption takes place may typically be higher thanthe first temperature at which adsorption of the first fluid componentis performed. In an embodiment of the present invention in which the TSAmethod comprises an intermediate pre-regeneration step, thepre-regeneration step may comprise desorbing and/or displacing at leasta portion of undesirably adsorbed second or diluent fluid component fromthe adsorbent material, which may be conducted at another intermediatetemperature or temperature range, which may preferably be between thefirst adsorbent material temperature during adsorption, and the secondadsorbent material temperature during regeneration or desorption of thefirst fluid component during a desorbing step. In an embodiment of thepresent invention in which the TSA method comprises a conditioning step,the conditioning step may comprise conditioning the at least oneadsorbent material to a desired pre-adsorption temperature prior toadmitting the feed fluid mixture into the contactor for adsorption. Inone such embodiment, the conditioning step may comprise admitting atleast one conditioning fluid which may comprise a heat transfer fluidinto the parallel passage adsorbent contactor to transfer heat to and/orfrom the adsorbent contactor by direct contact of the conditioningand/or heat transfer fluid with the contactor so as to condition theadsorbent material in the contactor to the desired pre-adsorptiontemperature. Any suitable known conditioning and/or heat transfer fluidsmay be used in such a pre-conditioning step, such as but not limited toair, steam, water, coolants, condensable solvents, vapors, etc. In oneembodiment, the desired pre-adsorption temperature may typically belower than the first temperature at which adsorption takes place,however, in an alternative embodiment, the pre-adsorption temperaturemay be higher than the first adsorption temperature, but lower than thesecond desorption temperature, for example. In a further relatedembodiment, such a conditioning step may desirably comprise providing asecondary purge of the adsorbent material in the parallel passageadsorbent contactor, so that following a first purge during thedesorption step, a secondary purge fluid stream is passed through thecontactor and thereby in contact with the at least one adsorbentmaterial to condition the adsorbent material to a desired pre-adsorptiontemperature and/or to further desorb or sweep one or more fluidcomponents from the adsorbent material prior to resumption of the nextadsorption step in the present TSA method, for example.

In another embodiment of the present invention, the parallel passageadsorbent contactor may comprise at least first and second adsorbentmaterials, wherein at least a portion of the first fluid component isadsorbed on at least the first adsorbent material during the adsorptionstep. In one exemplary configuration, the first and second adsorbentmaterials may be comprised in separate first and second axial segmentsof the adsorbent contactor with one segment upstream of the othersegment in the adsorbent contactor structure. In one such embodiment,where the first adsorbent material adsorbs at least a portion of thefirst fluid component from the feed fluid mixture, the desorption stepof the present TSA method may provide for desorbing at least a portionof the adsorbed first fluid component from the first adsorbent materialby heating the first adsorbent material, separate from and substantiallywithout heating the second adsorbent material. In one such embodiment,the thermally conductive filaments in the adsorbent contactor maydesirably also be electrically conductive, and such separate heating ofthe first adsorbent material during the desorption step may beaccomplished by applying an electrical current only to the filaments incontact with the first adsorbent material in order to heat the firstadsorbent material and desorb the first fluid component therefromwithout substantially heating the second adsorbent material.

In another embodiment, the desorption step of the present TSA method mayadditionally comprise supplying a suitable purge fluid into the parallelpassage adsorbent contactor during desorption, and recovering anadsorbed product fluid comprising both the first fluid component and thepurge fluid from the contactor. In one such embodiment, the purge fluidmay be supplied to at least one of the inlet and outlet ends of theadsorbent contactor during the desorption step and may pass through theparallel passage flow channels in the adsorbent contactor in at leastone of the first and second axial directions as part of the desorptionof the first fluid component from the at least one adsorbent material.The purge fluid may also be used to provide at least a portion of theheat required to heat the adsorbent material during the desorption step(or an intermediate pre-regeneration step in an alternative embodiment)of the present TSA method. In one aspect, the adsorbent material may beheated during the desorption step by supplying at least one purge orheat transfer fluid at an elevated temperature into the parallel passagefluid contactor. In another embodiment, the desorption step may comprisedirectly heating at least one adsorbent material to desorb the firstfluid component by means of heating the thermally conductive filamentsof the contactor and thereby directly heating the cell walls of theparallel passage contactor which comprise the adsorbent material. In onesuch embodiment, the thermally conductive filaments may be heated by asource of sensible heat, or alternatively in an embodiment where thethermally conductive filaments are also electrically conductive, thefilaments, and thereby the adsorbent material in the cell walls of thecontactor may be directly heated by passing an electrical currentthrough the filaments such as by electrical resistance or joule heatingof the filaments. In a particular aspect, the use of electricalresistance or joule heating of the conductive filaments in the contactorto directly and precisely heat the adsorbent material(s) duringdesorption may desirably provide for reduced cycle times for the TSAmethods of the invention, and may allow for reduction of theconventionally long (typically hours or more) cycle durations tosignificantly shorter cycle durations such as TSA steps (such asadsorption, desorption, etc.) of less than two minutes, and preferablyless than 90 seconds in duration, for example.

In a particular embodiment where the parallel passage contactor alsocomprises first and second adsorbent materials in corresponding firstand second axial segments of the contactor, the desorption step maycomprise desorbing at least a portion of the adsorbed first fluidcomponent from the first adsorbent material by electrically heating theconductive filaments in the first axial segment of the contactorseparately from the second adsorbent material in the second axialsegment. In a further embodiment, the first and second axial segmentsmay be sequentially heated such as by electrical resistance heating ofthe first and second segments individually during the desorption step ofthe present TSA method. In one such embodiment, the first axial segmentmay be located nearest to the outlet end of the contactor and the secondaxial segment may be located towards the inlet end of the contactor fromthe first segment, and corresponding to the sequential desorption of thefirst and second axial segments first and second desorbed product fluidsenriched in the first fluid component and another fluid componentdesorbed from the second adsorbent material may be recovered from theinlet or outlet end (depending upon the direction of fluid flow throughthe contactor during desorption) during the recovery step of the presentTSA method.

According to one embodiment of the present TSA method, any suitableknown adsorbent material such as those which may be used to adsorb adesired fluid component of the feed fluid mixture may be used inconjunction with the TSA method as the adsorbent material(s) comprisedin and/or on the cell walls of the parallel passage adsorbentcontactor(s). In a preferred embodiment, such adsorbent material maydesirably provide a sufficiently high dynamic selectivity (such ascomprising equilibrium and/or kinetic selectivity) of a first fluidcomponent relative to the remaining components of the feed fluid, overthe TSA cycle. In certain embodiments where the contactor(s) utilized inthe present TSA method comprise two or more segments or sections, suchas two or more axially spaced segments of the parallel passage adsorbentcontactors, any suitable known adsorbent materials may be comprised ineach of the contactor segments so as to provide for desired adsorptionof one or more fluid components from the feed fluid mixture. In one suchembodiment, the adsorbent contactor may comprise multiple separatesegments or sections comprising the same adsorbent material orcombination of adsorbent materials, and in another embodiment, theadsorbent contactor may comprise a different adsorbent material (orcombination of adsorbent materials) comprised in each of the contactorsegments or sections, such as to selectively adsorb different fluidcomponents of the feed fluid mixture during an adsorption step of thepresent TSA method. In such cases where multiple different adsorbentmaterials are implemented in the segments or sections of an adsorbentcontactor, desirably the adsorbent materials may be selected so as to becompatible with each other for adsorption of the particular feed fluidcomponents and at the intended adsorption and desorption conditions, forexample.

Exemplary known adsorbent materials which may be suitable for use inselected embodiments of the present TSA method may comprise, but are notlimited to: desiccant, activated carbon, carbon adsorbent, graphite,carbon molecular sieve, activated alumina, molecular sieve,aluminophosphate, silicoaluminophosphate, zeolite adsorbent, ionexchanged zeolite, hydrophilic zeolite, hydrophobic zeolite, modifiedzeolite, natural zeolites, faujasite, clinoptilolite, mordenite,metal-exchanged silico-aluminophosphate, uni-polar resin, bi-polarresin, aromatic cross-linked polystyrenic matrix, brominated aromaticmatrix, methacrylic ester copolymer, graphitic adsorbent, carbon fiber,carbon nanotube, nano-materials, metal salt adsorbent, perchlorate,oxalate, alkaline earth metal particle, ETS, CTS, metal oxide,chemisorbent, amine, organo-metallic reactant, and metal organicframework adsorbent materials, and combinations thereof.

In one embodiment of the TSA method of the present invention, the stepsof the TSA method may be desirably conducted under substantiallyconstant or isobaric pressure conditions. In a particular embodiment,the admission of feed fluid to the adsorbent contactor, adsorption of afluid component, recovery of a first product fluid, desorption of anadsorbed component, and recovery of a desorbed second product fluid mayall be conducted under substantially atmospheric pressure, for example.In an alternative embodiment, such steps of the present TSA method maybe conducted at a substantially constant elevated pressure, such asunder isobaric super-atmospheric conditions, for example. In anotheralternative embodiment, the admitting, adsorbing and recovering a firstproduct fluid steps of the present TSA method may be conducted under afirst substantially constant pressure condition, such as underatmospheric pressure, for example, while the desorbing and recovering adesorbed second product fluid steps may be conducted at an elevatedpressure, such as an elevated super-atmospheric pressure. In one suchembodiment, the adsorbent contactor may be substantially sealed prior tothe desorbing step, and the heating of the adsorbent contactor conductedduring the adsorbing step may result in increased pressure within thecontactor as the adsorbed fluid component desorbs from the adsorbentmaterial, thereby raising the pressure of the contactor to asuper-atmospheric level, for example. In this way the desorbed secondproduct fluid may optionally be recovered at a desirably elevatedpressure above the pressure at which the adsorbing steps were conducted,so as to provide a pressurized second product fluid which may bedesirable in certain applications.

In a particular aspect according to the present invention, a temperatureswing adsorption (TSA) process particularly directed to separatingcarbon dioxide gas from a flue gas feed mixture comprising at leastcarbon dioxide and nitrogen components is provided. Such a TSA processfor separating carbon dioxide may be particularly adapted for removingat least a portion of carbon dioxide from the flue gas or exhaust of athermal power plant, such as a coal or natural gas power plant forexample. In one embodiment directed to removal of carbon dioxide from aflue gas feed mixture, a temperature swing adsorption (TSA) process isprovided for separating at least a carbon dioxide component from theflue gas feed fluid mixture comprising at least carbon dioxide andnitrogen. In such an embodiment, the TSA process may comprise an initialstep of admitting the flue gas feed mixture into an adsorptiveseparation system which comprises at least one parallel passageadsorbent contactor. In particular, suitable such parallel passageadsorbent contactors may comprise a plurality of substantially parallelfluid flow passages oriented in a first axial direction between andinlet and outlet end of the contactor in order to permit fluid to flowthrough the contactor, and cell walls which comprise at least one carbondioxide adsorbent material situated between and separating the fluidflow passages. The parallel passage adsorbent contactor may alsodesirably comprise a plurality of axially continuous thermallyconductive filaments oriented in the axial direction of the contactorand in direct contact with the at least one carbon dioxide adsorbentmaterial comprised in or on the cell walls of the contactor. The fluegas may then be admitted into the inlet end of the parallel passageadsorbent contactor to flow in a first axial direction through thecontactor towards the outlet end, and at least a portion of the carbondioxide component may be adsorbed on the at least one carbon dioxideadsorbent material, which may preferably be selective for adsorbingcarbon dioxide over nitrogen and/or other components of the flue gasmixture.

In the present embodiment, heat released from the heat of adsorption ofthe carbon dioxide component on the at least one carbon dioxideadsorbent material is then transferred along at least a portion of thethermally conductive filaments in the adsorbent contactor in a secondaxial direction (opposite in direction to the first axial direction)back along the contactor towards the inlet end of the contactor duringthe adsorption of carbon dioxide on the carbon dioxide adsorbentmaterial. Such transfer of heat in the second axial direction maydesirably reduce a spike in the temperature of the at least one carbondioxide adsorbent as adsorption of carbon dioxide occurs, and optionallyalso desirably retain at least a significant portion of the heat energyfrom the heat of adsorption within the adsorbent contactor to allowrecovery of such thermal energy during later regeneration of the carbondioxide adsorbent material. A flue gas product stream depleted in carbondioxide relative to the flue gas feed mixture is then recovered from theoutlet end of the adsorbent contactor. In embodiments directed toremoving carbon dioxide from thermal power plant flue gas, such firstproduct fluid may desirably comprise a substantially carbon dioxide-freeflue gas product stream, which may then be vented to atmosphere orotherwise treated or processed prior to release and which may thereforebe expected to have a significantly lessened impact on carbon emissionsdue to the removal of carbon dioxide, as may be desirable for reducingimpact on atmospheric carbon dioxide levels for example. Following suchrecovery of the flue gas product stream, at least a portion of thecarbon dioxide adsorbed on the at least one carbon dioxide adsorbentmaterial is then desorbed by heating the at least one adsorbentmaterial, and heat is transferred in either of the first or second axialdirections along at least a portion of the thermally conductivefilaments of the adsorbent contactor to provide at least a portion ofthe heat of desorption of the carbon dioxide from the adsorbent materialwhich is required during the desorption step. Finally, a desorbed carbondioxide product enriched in carbon dioxide is recovered from at leastone of the inlet and outlet ends of the parallel passage adsorbentcontactor.

The present TSA carbon dioxide separation process according to the aboveembodiment may then optionally be repeated in the parallel passageadsorbent contactor to provide for a continuous or repeated cyclicseparation method for separating carbon dioxide from the flue gas feedmixture. In particular, similar to as described above in otherembodiments, an adsorptive separation system for operation according tothe present TSA carbon dioxide separation process may desirably comprisetwo or more such parallel passage adsorbent contactors, so as to providefor staggered operation of the present TSA separation process and allowcontinuous and/or semi-continuous adsorptive separation from a source offlue gas such as a thermal power plant, for example. As described above,any suitable known adsorptive separation system usingmechanical/pneumatic or other types of valves or other flow controldevices for example may be used to implement the gas flows of the stepsof the present TSA process, as are known in the art for systemscomprising one, two, or three or more adsorbers containing adsorbentmaterial.

Similar to as described above, in one embodiment of the presentinvention, an adsorptive separation system suitable for implementing thecarbon dioxide separation process comprises at least one parallelpassage adsorbent contactor which each comprise a plurality ofsubstantially parallel fluid flow passages oriented in a first axialdirection between and inlet and outlet end of the contactor in order topermit gas to flow through the contactor, and cell walls which compriseat least one carbon dioxide selective adsorbent material situatedbetween and separating the fluid flow passages. Each suitable suchparallel passage adsorbent contactor further comprises a plurality ofaxially continuous thermally conductive filaments oriented in the axialdirection of the contactor and in direct contact with the at least onecarbon dioxide adsorbent material comprised in the cell walls of thecontactor. As described above, certain such parallel passage adsorbentcontactor structures which may be suitable for use in implementing theTSA carbon dioxide separation process according to an embodiment of thepresent invention are described in the applicant's co-pending PCTInternational patent application filed as PCT/CA2010/000251, thecontents of which are herein incorporated by reference as though theyhad formed part of this application as originally filed. One particularparallel passage adsorbent contactor configuration suitable forimplementation of the TSA carbon dioxide separation process according toan embodiment of the present invention is shown in FIGS. 1 and 2 asdescribed above. In an optional embodiment, suitable parallel passageadsorbent contactors may comprise a plurality of continuous orsubstantially continuous thermally (and/or electrically) conductivefilaments oriented at least one of the axial direction (parallel to thedirection of fluid flow through the adsorbent contactor) and transversedirection (transverse relative to the axial direction).

In one embodiment, the TSA carbon dioxide separation process may alsocomprise a conditioning step to condition at least one carbon dioxideadsorbent in the adsorbent contactor(s) to a desired pre-adsorptiontemperature prior to admitting the flue gas feed mixture and adsorptionof carbon dioxide. Similar to as described above in other embodiments,such a conditioning step may comprise conditioning at least one carbondioxide adsorbent material to any desired or suitable pre-adsorptiontemperature, such as a temperature lower than an adsorption temperatureof the carbon dioxide adsorbent during an adsorption step of the TSAprocess, or higher than the adsorption temperature but lower than adesorption temperature of the adsorbent during a desorption step of theTSA process, for example. Also, similar to as described above, theadsorption temperature of the carbon dioxide adsorbent may desirably belower than the desorption temperature during a desorption step, suchthat the desorption of carbon dioxide from the adsorbent may beaccomplished by heating the adsorbent material, such as by directheating of the thermally conductive filaments in the adsorbentcontactor, for example.

In a particular embodiment, the TSA carbon dioxide separation processmay be applied to separate carbon dioxide from the flue gas from athermal power plant such as a coal fired boiler flue gas, so as todesirably substantially remove the carbon dioxide from the flue gas toallow capture of the carbon dioxide and thereby significantly decreasecarbon emissions of the power plant. In one such embodiment, the coalfired boiler flue gas feed mixture may comprise approximately 12% carbondioxide, 84% nitrogen and oxygen, and 4% water vapor, and may besupplied at approximately atmospheric pressure (101.3 kPa) and at atemperature of about 40 C, for example. In such a case, a suitablecarbon dioxide adsorbent material may be used in the parallel passageadsorbent contactor(s) of the adsorptive separation system to adsorbsubstantially all of the carbon dioxide from the flue gas during theadsorption step of the TSA process, and to recover a substantiallycarbon dioxide-free flue gas product stream.

In a preferred embodiment of the present invention, at least one carbondioxide selective adsorbent material comprised in the parallel passageadsorbent contactor may desirably be dynamically selective foradsorption of carbon dioxide over nitrogen or other diluent componentsof the flue gas mixture, such that a dynamic selectivity for carbondioxide is sufficiently high to usably provide substantially completecarbon dioxide separation. Such dynamic selectivity over the cycle ofthe TSA separation method may comprise at least one of an equilibriumselectivity of the at least one adsorbent material for carbon dioxide,and a kinetic selectivity of the at least one adsorbent material forcarbon dioxide. In one such preferred embodiment, the flue gas mixturemay be admitted to the adsorbent contactor at a space velocity(Vgas/Vads/t) less than the mass transfer rate (1/s) of carbon dioxide,but greater than the mass transfer rate (1/s) of nitrogen or otherdiluent components, such that the adsorption step may comprise at leasta kinetic selectivity based on the mass transfer rates of carbon dioxideand nitrogen on the adsorbent material at the adsorbent temperatureduring the adsorption step.

In the desorption step of the TSA process, a steam purge gas may besupplied to the adsorbent contactor, such as from the outlet end, andsuch as at a temperature of about 130 C and pressure of about 105 kPa,to assist in desorption along with the heating of the adsorbent with thethermally conductive filaments in the contactor. In one such case, ascarbon dioxide is desorbed from the adsorbent material during thedesorption step, a portion of the steam purge gas may be adsorbed by theadsorbent material which may release heat due to the heat of adsorptionof the steam, which heat may also be transferred axially along thecontactor by the thermally conductive filaments, which may desirablyfurther provide a portion of the heat of desorption necessary forcontinued desorption of carbon dioxide. The recovered carbon dioxideproduct from the adsorbent contactor may desirably be highlyconcentrated in carbon dioxide such as to allow for compression,storage, sequestration, or alternative industrial use (such as forinjection use in enhanced oil recovery for example) of the carbondioxide removed from the flue gas. In one such embodiment, the steamcomponent of the recovered carbon dioxide product stream may desirablybe condensed in order to remove it from the product stream, therebyresulting in increased purity of the carbon dioxide product. In anotherembodiment, the purge gas may also comprise at least one of ambient air,steam, and a flue gas product stream depleted of carbon dioxide. In yetanother embodiment, a heat transfer fluid may also be admitted to thecontactor during the desorption step, such as at an elevated temperatureto heat the adsorbent material, and may be used in addition to or inplace of a purge gas. Such heat transfer fluid may comprise at least oneof ambient air, steam, a carbon dioxide enriched product gas, or a fluegas product stream depleted of carbon dioxide, for example. In aparticular embodiment, the carbon dioxide adsorbent material may also bedirectly heated by heating the thermally conductive filaments in theadsorbent contactor, such as by applying sensible heat to the filaments,or in the case of electrically conductive filaments, applying anelectrical current to directly heat the filaments by electricalresistance or joule heating. In an alternative embodiment, a steam purgegas (or optionally another suitable purge gas or fluid or heat transferfluid), may alternatively be admitted from the inlet end or anotherlocation along the parallel passage contactor so as to provide for flowof purge gas in the same direction as the feed fluid, opposite to thefeed fluid direction, or both, for example.

In an alternative embodiment, as may be particularly desirable inapplications to separate carbon dioxide from flue gas streams havingrelatively dilute carbon dioxide concentrations such as less than about10% and more particularly less than about 5%, the TSA process mayadditionally comprise an intermediate recycle or pre-regeneration stepin which a limited amount of heat is provided to the adsorbent materialto heat the contactor to an intermediate temperature sufficient todesorb at least a portion of an undesired nitrogen (or other diluent)component co-adsorbed on the adsorbent material. In such case, theadsorbent material may be heated using any suitable means, such as oneor more of: providing a heated purge gas, heated recycle gas or heatedcarbon dioxide product gas to the adsorbent contactor, and/or direct orelectrically heating the conductive filaments in the adsorbentcontactor, for example. The resulting recycle stream leaving theadsorbent contactor during such step may then be recycled within the TSAprocess such as to provide heat for another desorption orpre-regeneration step and/or recycled to the feed stream forre-admission during subsequent adsorption or feed steps. In analternative embodiment, during such an intermediate recycle orpre-regeneration step, a heated purge gas, recycle gas or carbon dioxideproduct gas (such as steam or optionally another suitable purge gas orfluid or heat transfer fluid), may alternatively be admitted from theinlet end or another location along the parallel passage contactor so asto provide for flow of heated pre-regeneration fluid in the samedirection as the feed fluid, opposite to the feed fluid direction, orboth, for example.

Following the recovery of the carbon dioxide product, the present TSAprocess may also comprise a conditioning step where ambient air at lessthan about 40 C and at substantially atmospheric pressure (101.3 kPa)may be admitted at the inlet end of the contactor, to condition theadsorbent material prior to resuming the adsorption step on the nextcycle. The conditioning step may desirably cool the adsorbent materialby removal of sensible heat from the adsorbent material by the ambientair, and also to remove at least a portion of the water adsorbed on theadsorbent material from the steam purge gas, thereby drying theadsorbent material prior to the next adsorption step, and also furthercooling the adsorbent material due to the heat removed by desorption ofthe water from the adsorbent material during drying. However, in someembodiments, such cooling step using air as a cooling fluid may resultin adsorption of at least a portion of nitrogen or other diluents on theadsorbent material, thereby necessitating the above-describedpre-regeneration or recycle step in order to preserve high purity in thedesorbed carbon dioxide product recovered during the regeneration of theadsorbent contactor, as may be desirable for carbon sequestration,compression and/or enhanced oil recovery injection of carbon dioxideapplications.

In certain embodiments of the present TSA carbon dioxide separationprocess, any suitable known carbon dioxide adsorbent material may beused in the parallel passage adsorbent contactor(s) of the adsorptiveseparation system to adsorb carbon dioxide during the adsorption step ofthe process. Potentially suitable such carbon dioxide adsorbents maycomprise, but are not limited to: activated carbon adsorbent, amineimpregnated adsorbent supports (comprising silica, activated carbon,carbon molecular sieve, alumina, zeolite, polymer and ceramic supports),metal salt, metal hydroxide, metal oxide, zeolite, hydrotalcite,silicalite, metal organic framework and zeolitic imadazolate frameworkadsorbent materials, and combinations thereof. In a particularembodiment, a suitable carbon dioxide adsorbent material may be selectedthat may also desirably be selective for the adsorption of carbondioxide over any other gas components of the flue gas feed mixture, forexample. In a particular embodiment, such suitable carbon dioxideselective adsorbent material may desirably be tailored for high dynamicselectivity of carbon dioxide over nitrogen. Such desirable high dynamicselectivity carbon dioxide adsorbent may thereby be chosen so as tomaximize equilibrium and kinetic selectivity for carbon dioxide overnitrogen (and/or other diluents fluid species) in a cyclic TSA processby either selecting an adsorbent with such characteristics or tailoringthe properties of the parallel passage contactor and/or modifying thesurface characteristics of adsorbent material comprised in the parallelpassage contactor such as by modifying the adsorbent material pore size,pore throat, pocket size, etc., to improve equilibrium and/or kineticselectivity of carbon dioxide, for example.

Similar to as described above in other embodiments, in one embodiment ofthe present TSA carbon dioxide separation process, the adsorbentcontactor may comprise at least one first carbon dioxide adsorbent andalso at least one second adsorbent material. Such first and secondadsorbent materials may comprise similar or different adsorbentmaterials and may be comprised in first and second segments of theadsorbent contactor, such as first and second axial segments forexample. In such a case the desorption step of the TSA carbon dioxideseparation process may comprise desorbing at least a portion of theadsorbed carbon dioxide from the first adsorbent material byelectrically heating the conductive filaments in the first axial segmentof the contactor separately from the second adsorbent material in thesecond axial segment. In a further embodiment, the first and secondaxial segments may be sequentially heated such as by electricalresistance heating of the first and second segments individually duringthe desorption step of the present TSA method, so as to produce aseparate first carbon dioxide rich product gas, and a second product gasenriched in another flue gas component desorbed from the secondadsorbent material. In one such embodiment, the first axial segment maybe located nearest to the outlet end of the contactor and the secondaxial segment may be located towards the inlet end of the contactor fromthe first segment, and corresponding to the sequential desorption of thefirst and second axial segments first and second desorbed product fluidsenriched in carbon dioxide and another flue gas component desorbed fromthe second adsorbent material may be recovered from the inlet or outletend (depending upon the direction of fluid flow through the contactorduring desorption) during the recovery step of the present TSA method.In another embodiment, three or more axial segments and correspondingadsorbent materials may be implemented including the first carbondioxide adsorbent, and may thereby be sequentially and individuallydesorbed in order to produce a separate carbon dioxide enriched productstreams and corresponding other product streams which may be recoveredseparately from the adsorbent contactor. In a particular embodiment, asecond adsorbent material selective for at least one of water, nitrogenoxides, sulfur oxides and heavy metals over carbon dioxide,respectively, and optionally also a third adsorbent material selectivefor at least one of water, nitrogen oxides, sulfur oxides and heavymetals over carbon dioxide may be implemented in separate second andthird axial segments in addition to the carbon dioxide adsorbent in afirst axial segment of the contactor, such that the second axial segmentis located upstream of said first axial segment nearer to the inlet endof said contactor, and wherein said third axial segment is locatedupstream of said first axial segment and downstream of said second axialsegment. Such second and third adsorbent materials may thereby be usedto desirably separate other contaminants from the flue gas stream whichmay be separately desorbed and recovered such as for containment and/ordisposal separate from the carbon dioxide product.

Similar to as described above in other embodiments, in one embodiment ofthe present TSA carbon dioxide separation process, the steps of the TSAprocess may be desirably conducted under substantially constant orisobaric pressure conditions. In a particular embodiment, the admissionof the flue gas feed mixture to the adsorbent contactor, adsorption ofcarbon dioxide, recovery of a flue gas product stream, desorption ofcarbon dioxide, and recovery of a desorbed carbon dioxide stream may allbe conducted under substantially atmospheric pressure, for example. Inan alternative embodiment, such steps of the present TSA process may beconducted at a substantially constant elevated pressure, such as underisobaric super-atmospheric conditions, for example. In anotheralternative embodiment, the admitting, adsorbing and recovering a fluegas product stream steps of the present TSA process may be conductedunder a first substantially constant pressure condition, such as underatmospheric pressure, for example, while the desorbing and recovering adesorbed carbon dioxide product steps may be conducted at an elevatedpressure, such as an elevated super-atmospheric pressure. In one suchembodiment, the adsorbent contactor may be substantially sealed prior tothe desorbing step, and the heating of the adsorbent contactor conductedduring the adsorbing step may result in increased pressure within thecontactor as the adsorbed carbon dioxide desorbs from the adsorbentmaterial, thereby raising the pressure of the contactor to asuper-atmospheric level, for example. In this way the desorbed carbondioxide product fluid may optionally be recovered at a desirablyelevated pressure above the pressure at which the adsorbing steps wereconducted, so as to provide a pressurized carbon dioxide product streamwhich may be desirable in certain applications, such as where furthercompression of the carbon dioxide may be required for transport,storage, sequestration or industrial use.

In another aspect of the present invention, the temperature swingadsorption (TSA) carbon dioxide separation process may be particularlydirected to separating carbon dioxide gas from a natural gas feedmixture in place of a flue gas feed mixture. In such embodiments, thenatural gas feed mixture may comprise at least methane and carbondioxide components, and may also comprise hydrogen sulfide or othercontaminants. Such a TSA process for separating carbon dioxide fromnatural gas may be particularly adapted for removing at least a portionof the carbon dioxide and/or hydrogen sulfide from a contaminatednatural gas feed mixture, as may be encountered in applications such asshale gas, low concentration natural gas fields or end of well lifenatural gas sources, for example. In such cases, the TSA carbon dioxideseparation process may be relatively similar to that for flue gasseparation, substituting the natural gas feed stream for the flue gas.Any suitable adsorbent material may be comprised in the adsorbentcontactor(s) of the adsorptive separation system which are desirablyselective for carbon dioxide and/or hydrogen sulfide over other naturalgas components, and preferably desirably dynamically selective(comprising equilibrium and/or kinetic selectivity) for carbon dioxideand/or hydrogen sulfide (or other undesirable diluent components) overmethane over the cyclic TSA process. In a particular embodiment, suchsuitable carbon dioxide selective adsorbent material may desirably betailored for high dynamic selectivity of carbon dioxide over methane.Such desirable high dynamic selectivity carbon dioxide adsorbent maythereby be chosen so as to maximize equilibrium and kinetic selectivityfor carbon dioxide over methane in a cyclic TSA process by eitherselecting an adsorbent with such characteristics or tailoring theproperties of the parallel passage contactor and/or modifying thesurface characteristics of adsorbent material comprised in the parallelpassage contactor such as by modifying the adsorbent material pore size,pore throat, pocket size, etc., to improve equilibrium and/or kineticselectivity of carbon dioxide, for example. Also, such natural gascarbon dioxide separation processes may typically be conducted atisobaric super-atmospheric pressures associated with pressurized naturalgas feed mixture sources such as wells and/or pipelines, for example.

The exemplary embodiments herein described are not intended to beexhaustive or to limit the scope of the invention to the precise formsdisclosed. They are chosen and described to explain the principles ofthe invention and its application and practical use to allow othersskilled in the art to comprehend its teachings.

As will be apparent to those skilled in the art in light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined by the followingclaims.

What is claimed is:
 1. An adsorption method for separating a fluidmixture comprising at least first and second fluid components, themethod comprising: admitting said fluid mixture into an adsorptiveseparation system comprising at least one parallel passage adsorbentcontactor, said parallel passage adsorbent contactor comprising a firstaxial direction between an inlet and an outlet end thereof andcomprising at least one adsorbent material; admitting said fluid mixtureinto said inlet end of said parallel passage adsorbent contactor to flowtowards said outlet end in said first axial direction; adsorbing atleast a portion of said first fluid component on said at least oneadsorbent material; transferring heat from a heat of adsorption of saidfirst fluid component on said at least one adsorbent material along saidparallel passage adsorbent contactor in an axial direction during saidadsorbing step; recovering a first product fluid depleted in said firstfluid component relative to said fluid mixture from said outlet end;admitting a purge fluid into said parallel passage adsorbent contactorto flow in a second axial direction; desorbing at least a portion ofsaid first fluid component adsorbed on at least one said adsorbentmaterial by heating at least one said adsorbent material; transferringsaid heat of adsorption along said parallel passage adsorbent contactorin said second axial direction to provide at least a portion of the heatof desorption of said first fluid component during said desorbing step;and recovering a desorbed second product fluid enriched in said firstfluid component from at least one of said inlet and said outlet ends. 2.The adsorption method according to claim 1, additionally comprisingadmitting a pre-regeneration fluid into said parallel passage adsorbentcontactor and desorbing at least a portion of said second fluidcomponent co-adsorbed on said at least one adsorbent material by heatingsaid at least one adsorbent material to a pre-regeneration temperature,prior to admitting said purge fluid.
 3. The adsorption method accordingto claim 2, additionally comprising admitting said pre-regenerationfluid into said parallel passage adsorbent contactor to flow towardssaid inlet end in a second axial direction.
 4. The adsorption methodaccording to claim 1, wherein said at least one adsorbent material iskinetically selective for said first fluid component and has a firstmass transfer rate for said first fluid component which is greater thana second mass transfer rate for said second fluid component.
 5. Theadsorption method according to claim 4, wherein admitting said fluidmixture comprises admitting said fluid mixture into said inlet end ofsaid parallel passage adsorbent contactor to flow towards said outletend in said first axial direction wherein said fluid mixture is admittedat a space velocity greater than said second mass transfer rate for saidsecond fluid component and less than said first mass transfer rate forsaid first fluid component.
 6. The adsorption method according to claim1, additionally comprising conditioning at least one said adsorbentmaterial to a desired pre-adsorption temperature prior to admitting saidfluid mixture into said parallel passage adsorbent contactor.
 7. Theadsorption method according to claim 1 wherein said parallel passageadsorbent contactor comprises at least first and second adsorbentmaterials, and wherein said desorbing comprises desorbing at least aportion of said first fluid component adsorbed on said first adsorbentmaterial by heating said first adsorbent material separately from saidsecond adsorbent material.
 8. The adsorption method according to claim1, wherein said purge fluid is condensable, and additionally comprisingcondensing said purge fluid out of said desorbed product fluid followingrecovering said desorbed product fluid.
 9. The adsorption methodaccording to claim 1, wherein said desorbing additionally comprisesheating at least one said adsorbent material by supplying at least oneheat transfer fluid at an elevated temperature into said parallelpassage adsorbent contactor.
 10. The adsorption method according toclaim 1, wherein said desorbing additionally comprises directly heatingat least one said adsorbent material by supplying thermal energy to aplurality of contactor cell walls comprising said at least one adsorbentmaterial.
 11. The adsorption method according to claim 6, wherein saidconditioning further comprises providing a secondary purge of said atleast one adsorbent material prior to admitting said fluid mixture. 12.The adsorption method according to claim 1, wherein said transferringsaid heat of adsorption along at least a portion of said contactorduring said adsorbing step is effective to reduce a thermal profilespike in said parallel passage adsorbent contactor associated with saidadsorbing of said first fluid component on said at least one adsorbentmaterial.
 13. The adsorption method according to claim 1, wherein saidat least one adsorbent material is selected from the list consisting of:desiccant, activated carbon, carbon molecular sieve, carbon adsorbent,graphite, activated alumina, molecular sieve, aluminophosphate,silicoaluminophosphate, zeolite adsorbent, ion exchanged zeolite,hydrophilic zeolite, hydrophobic zeolite, modified zeolite, naturalzeolites, faujasite, clinoptilolite, mordenite, metal-exchangedsilico-aluminophosphate, uni-polar resin, bi-polar resin, aromaticcross-linked polystyrenic matrix, brominated aromatic matrix,methacrylic ester copolymer, graphitic adsorbent, carbon fiber, carbonnanotube, nano-materials, metal salt adsorbent, perchlorate, oxalate,alkaline earth metal particle, ETS, CTS, metal oxide, chemisorbent,amine, organo-metallic reactant, and metal organic framework adsorbentmaterials, and combinations thereof.
 14. The adsorption method accordingto claim 1, wherein said admitting, adsorbing, recovering a firstproduct fluid, desorbing and recovering a desorbed second product fluidsteps are substantially isobaric and are conducted at one ofsubstantially atmospheric and elevated supra-atmospheric pressures. 15.The adsorption method according to claim 1, wherein said fluid mixturecomprises a flue gas, said first fluid component comprises carbondioxide, and said second fluid component comprises nitrogen, and whereinsaid at least one adsorbent material comprises at least one carbondioxide adsorbent material.
 16. The adsorption process according toclaim 15, wherein said parallel passage adsorbent contactor comprises atleast first and second axial segments comprising a first adsorbentmaterial selective for carbon dioxide over nitrogen, and a secondadsorbent material selective for at least one of water, nitrogen oxides,sulfur oxides and heavy metals over carbon dioxide, respectively, andwherein said second axial segment is located upstream of said firstaxial segment nearer to the inlet end of said contactor.
 17. Theadsorption method according to claim 1, additionally comprisingadmitting at least one heat transfer fluid into said parallel passageadsorbent contactor to flow towards said inlet end in said first axialdirection.
 18. The adsorption method according to claim 1, additionallycomprising transferring said heat of adsorption in a transversedirection relative to said first axial direction.
 19. An adsorptionprocess for separating at least one of carbon dioxide and hydrogensulfide from a natural gas feed mixture comprising at least one ofcarbon dioxide and hydrogen sulfide and methane components, the processcomprising: admitting said natural gas feed mixture into an adsorptiveseparation system comprising at least one parallel passage adsorbentcontactor, said parallel passage adsorbent contactor comprising a firstaxial direction between an inlet and an outlet end thereof and at leastone adsorbent material; admitting said natural gas feed mixture intosaid inlet end of said parallel passage adsorbent contactor to flowtowards said outlet end in said first axial direction; adsorbing atleast a portion of at least one of said carbon dioxide and hydrogensulfide components on said at least one adsorbent material; transferringheat from a heat of adsorption on said at least one adsorbent materialalong at least a portion of said parallel passage adsorbent contactor inan axial direction during said adsorbing step; recovering a natural gasproduct stream depleted in at least one of carbon dioxide and hydrogensulfide relative to said natural gas feed mixture from said outlet end;admitting a purge fluid into said parallel passage adsorbent contactorto flow towards said inlet end in a second axial direction; desorbing atleast a portion of at least one of said carbon dioxide and hydrogensulfide adsorbed on at least one said adsorbent material by heating saidat least one adsorbent material; transferring said heat of adsorptionalong at least a portion of said parallel passage adsorbent contactor insaid second axial direction to provide at least a portion of the heat ofdesorption of said carbon dioxide or hydrogen sulfide during saiddesorbing step; and recovering a desorbed product enriched in at leastone of carbon dioxide and hydrogen sulfide from at least one of saidinlet and said outlet ends.
 20. The adsorption method according to claim19, additionally comprising transferring said heat of adsorption in atransverse direction relative to said first axial direction.